Screw conveyer



Patented Feb. 7, 1950 SCREW CONVEYEB Paul V. Whitney, olumbus, Ohio, assignor to rEhe Jeffrey Manufacturing Company, a corporation of Ohio Application March .29, 194e, seriarNo. :658,262

2 Claims. v1

This invention relates to conveyers and more particularly to conveyer-s .of the spiral, screw, or worm type.

The principal obj-ect of .my invention is to provide an improved conveyer of the spiral, screw, or worm type, which is capable of conveying objects in an upward direction, which objects normally cannot be successful-ly conveyed in a spiral, screw, or worm type conveyer because they tend to roll or slide downwardly on the helix, spiral, or worm member of the conveyer.

In carrying out the principal object, it is another object of my invention to provide in a spiral -conveyer a continuous shoulder which extends longitudinally of the wormor spiral t ^erect and cooperates with the casing of the conveyer to form a dam or pocket in the conveyer against or in which the objects being .conveyed may be directed by gravity and/or centrifugal force and are there retained while being conveyed through the conveyer by the driven worm `or spiral member thereof.

Other and further objects of the .invention will appear hereinafter the novel features and combinations being set forth in .the appended claims.

In the vaccompanying drawings,

Fig. l is a side sectional .elevational View of a spiral, screw or worm type conveyer that .embodies a form of my invention;

Fig. 2 is a view in rcross-section, the View being taken on line ,2--2 of Fig. 1; and

Fig. 3 is a diagrammatic view or layout on a larger scale showing a fragment .of a true helical screw or worm such as forms .a working member of the ,spiral conveyer, the worm in Fig. 3 being a screw of opposite pitch to that of Fig. 1.

Referring to Fig. l of the drawings wherein a spiral, screw or worm conveyer 4HJ is shown, the conveyer includes `a casing, housing or trough il which is connected to a feed hopper l2 .in which objects to be conveyed Vby the conveyer .are rcceived. A feed opening I3 in the casing 'il connects the casing and hopper and directs objects in the hopper into the conveyer casing. At its upper end the casing Il is provided with an outlet or discharge .chute Ill. Casing li, hopperiZ, and discharge chute Hl may be formed in any suitable manner, but preferably they are united so as to form a rigid assembly. The casing, housing or trough member ll of the conveyer, as shown, s U-shaped in ycross-section and is covered by a top plate 'I'5 the edges of which .are bolted to outwardly extending nanges i6 oi the member Il. A screw 'or worm flight member i8 is contained within the casing 'Ii and is mounted (Cl. 19E-213) 2 therein by its central core or shaft I9, the upper end of which extends through an end wall 20 of the discharge end of the conveyer' and is mounted in a bearing 2i carried thereby. The bottom .end wall of the casing is formed by a bracket 22 that includes a bearing 23 which supports the lower end of the central core or shaft I9. A sealing washer 2li is provided in the .conveyer casing adjacent the bottom end wall or bracket 22 for preventing dirt or other foreign matter lfrom entering the bearing 23. The lower end .of the shaft i9 carries a bevel gear 25 that meshes with a bevel gear 26 carried by a shaft 2i. Shaft .21

' is -bearinged in the bracket 2 2 and may be .driven to drive the screw or worm i8 through the gears 26 and '255 from any suitable source of power which may be, for example, an electric motor, not shown. The conveyer iii thus far described may follow in construction that of the well known spiral conveyors at present in use.

Known screw conveyers may be used for Aconveying objects which have a tendency to roll or slide when the conveyer is in a horizontal position because the force of gravity causes the objects to seek the lowest level possible in the conveyer. The lowest level in a horizontally positioned worm conveyer is, ofcourse, below the level oi the top of the central shaft of the worm. The area lbelow the top ofthe shaft is divided into a plurality of pockets by those portions of the worm which are .below the top of the Ashaft Aand as the worm is rotated the pockets, in effect, are moved Vtoward the discharge end of the conveyer and the objects therein are spilled from the Yconveyer.

Ii the screw conveyer is inclined so as to con- Vey the objects upwardly, the level orcapacity of each of the pockets is decreased. The level of each of the pockets is then determined by the lowest point on the top cf the central shaft of the worm above each pocket. As the incline of the conveyer is increased the capacity of the pockets is decreased until such time as the pitch or lead angle oi the worm is equalled by the central shait of the worm and a horizontal plane intersecting it, at which ltime vthe pockets cease to exist and the lobjects in the conveyer will roll or slide downwardly freely alongthe worm.

ACentrifugal force oi the Aobjects and friction between them and the worm also lcombine to play an important rdetrimental role since they tend to cause the objects to iollow or rotate with 'the worm to such extent, depending upon the incline of the conveyer, 4and :the speed of rotation of the worm and 'its lead or pitch angle, as to cause some or all of the objects to be carried from pocket to pocket in the conveyer.

The reasons for the above-mentioned faults of known screw conveyers for conveying objects which tend to roll or slide are discussed in detail hereinafter in connection with my invention which makes use of the eiects of gravity and centrifugal force of the objects and provides a simple remedy for the faults of known screw type conveyers lbriefly discussed above.

For the purpose of illustration of my invention, the worm 32, shown in Fig. 3, is of opposite pitch to the worm i8 of Fig. l. Assuming the worm 32 seen in Fig. 3 to be in a horizontally positioned conveyer casing, then a plurality of pockets or chambers 3| may be said to be defined in the lower portion of the housing by a propelling or front surface 33 of the worm 32 which engages objects to propel them, a back side the worm, and the top edge of a central core or shaft 35 of the worm 32. Further assuming, for the purpose of illustration, that a quantity, not great enough to lill the conveyer casing, of round objects, such as balls, are to be conveyed, the pockets 3l will be lled with them, and should the level of the balls in any given pocket exceed the height of the top of the central core or shaft 35 of the worm 32, those objects which are above the shaft will be spilled over the shaft into the next or following pocket 3l. Should the discharge end 3E of the conveyer be elevated to place the conveyer in an incline, the capacity of the pockets 3l is reduced.

Referring to the layout of the true helical worm shown in Fig. 3, the lines P|-Cl, P2-C2, etc., represent planes which are perpendicular to the axis of the central core or shaft 35, the points P showing the intersection of the outer periphery of the helical member of the worm and the planes and the points C showing the intersections of the inner periphery of the helical member of the worm and the planes or where the inner periphery of the helical member, the central core 35 and the planes P-C intersect. It will be seen in Fig. 3 that when the conveyer is placed in an inclined position, as by elevating the discharge end 35 of the conveyor, the level in eachpocket 3l, below which balls will be contained therein, will be determined gent with the highest point on the curve C, which curve is a line intersecting all of the points C on the propelling surface 33 of worm 32, and this will be true until the incline of the conveyer is increased to such degree that the horizontal fr plane or pocket level 31 becomes tangent with the curve C at the point C8. Should the angle of incline of the conveyer be increased beyond this degree the point C6 will remain tangent with the horizontal plane 31.

Considering all of the P-C planes which are perpendicular to the axis of the central core or shaft 35, where these planes intersect the helical member of the worm at their respective points P and C, any line P-C will intersect the axis of the central core or shaft, that is, they will be true radial lines. Considering now the line Pfl-C6 which appears as a point in Fig. 3 because the line PE--CS is horizontal, it will be seen that line P'l-Cl which is to the left of line PE--CB is below line PS-CG and slopes outwardly, downwardly from the point C1 to the point P1. Considering the line P5-C5 which is to the right of line PS-CG it will be seen that the plane of this line slopes inwardly from the 34 of the adjacent forward convolution of by a horizontal plane 31 tan- F point P5 to the point C5. Thus an object below the line PS-CB will tend to roll outwardly, downwardly and into the pocket or chamber 3|, and an object above the line Pil- C6 will tend to roll downwardly and inwardly and should the point C8 be tangent with the horizontal plane 31, the object will roll downwardly on the curve C and spill into the next pocket 3 l.

Actually when a screw, spiral or worm conveyer is in operation there is considerable friction between the flight of the worm and the objects being conveyed and this friction causes the objects to be carried upwardly across the plane PS-C and out of the pocket 3l into the next adjacent or following pocket. The action of the flight upon the objects being conveyed also causes the objects to be thrown outwardly against the casing Il of the conveyer.

A critical feature of my invention resides in the provision of an abutment member 28 within the casing il, the relationship between the inner surface of the casing l i and the periphery of the screw or worm i8, the relative position of the abutment member 28 with respect to the angle of incline of the conveyer i0 and the lead of the worm or helical member lil thereof.

It will be seen from a further description of my invention that the abutment member 2B must be placed in the conveyer in denite relation with the pitch or lead angle of the worm or helical member and the angle of incline of the conveyor in order to realize the maximum emciency of my improved conveyer.

The abutment member 28 as seen in Fig. 1 extends longitudinally within the casing l! from beneath the feed opening i3 to adjacent the outlet or discharge chute Hl. The abutment member 28 may, if desired, extend above the chute I4 but it should not extend to the upper end wall 28 of the casing Il.

In practising my invention, the diameter of the screw or worm i8 is such that a space 29 is provided between the outside or periphery of the worm I8 and the inside of the casing I I. The abutment 28 is shown as being formed of a continuous bar which may be welded or otherwise secured to the casing Il, but it is to be understood that any means may be employed which will provide an inwardly extending abutment or shoulder 3G (see Fig. 2). For example, the casing may be formed as by bending it to provide said shoulder 3U.

Referring again to Fig. 2, I have found that by providing the abutment member 28 or shoulder 33 in a position adjacent any of the points below the axis of shaft i9 depending upon the incline of the conveyer, objects which are directed outwardly, downwardly by gravity and centrifugal force into the pockets 3l will not be carried upwardly to the plane PS CB and that a plurality of objects may be successfully conveyed in an upward direction in a spiral conveyer. It will be seen, of course, that when the horizontal plane 31 lies substantially in the plane of the helix angle of outer periphery of the worm, the objects will be retained in a pocket or trough 38 substantially wholly by centrifugal force imparted to them by the rotating worm. However, in all angles of incline of the conveyer before the horizontal plane 31 coincides with the helix angle of the outer periphery of the worm, gravity plays an important role in assisting to retain the objects in the pocket or trough 38. In Fig. 2 a ball 3e is shown in the trough 38.

It will be understood by those skilled in the art that the position of the shoulder 30, represented in Fig. 2 by the angle F, will be nearer to the lowermost longitudinal plane of the casing as either or both the lead of the helix is increased or the angle of incline of the conveyer is increased up to that angle wherein the horizontal plane 31 coincides with the helix angle of the outer periphery of the worm, that is, as either of the above are increased the angle F is described.

In practice the worms or helical members of conveyers are not formed as true helices, how\ ever, while in the foregoing description of my invention I have described it in connection with a true helix it will be seen that the invention is equally applicable to conveyers wherein the worms are not true helices by changing the position of the shoulder 30 in accordance with the grade lines of the worms, that is, by determining the correct angle F for the given worm.

From the foregoing it will be seen that a conveyer constructed in accordance with my teachings is capable of conveying objects which tend to roll or slide when the conveyer is in a substantially vertical plane and that such objects will be conveyed upwardly in the trough 38 in a substantially continuous stream, that is, the objects will tend to stack, above and behind one another in the trough 38.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as dened by the claims hereto appended and I wish therefore not to be restricted to the precise construction herein disclosed.

I-Iaving thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

l. A screw conveyer adapted to convey objects upwardly which tend to roll including in combination a casing having inlet and discharge openings, a power driven worm in said casing, a longitudinally and inwardly extending abutment extending between said inlet and discharge openings parallel to the axis of said worm and extending inwardly of said casing and adjacent the outer edge of said worm, said abutment c0- operating with said casing and worm for forming pockets into which objects being conveyed are directed and moved by said worm toward said discharge opening, and means for rotating said worm in a direction whereby bottom peripheral portions of said worm move toward said abutment and whereby frictional contact between said worm and objects in the bottom of said casing moves said objects against said abutment.

2. A screw conveyer for conveying objects upwardly which tend to roll including in combination a casing having a longitudinally extending shoulder, a power driven worm in said casing, the outer peripheral surface of which rotates adjacent an edge of said shoulder, said shoulder being positioned so that objects in said conveyer are directed thereagainst and thereby prevented from moving downwardly in the conveyer, and means for rotating said worm in a direction whereby bottom peripheral portions of said worm move toward said shoulder and whereby frictional contact between said worm and objects in the bottom of said casing moves said objects against said shoulder.

PAUL V. WHITNEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Argall Nov. 19, 1912 Number 

